Barred owls are larger, more aggressive and less picky about what they eat than their cousins, and have taken over much of the spotted owl's territory in Oregon, Washington and Northern California. By shooting barred owls or using non-lethal removal methods in four test areas, researchers hope to document whether spotted owls will recover.

Robin Bown, a wildlife service biologist heading the project, said she doesn't expect full public support for killing barred owls to protect spotted owls.

"Some people will tell us it's OK to let them go extinct; we don't feel we can do that," she said. "We feel very strongly we have to deal with issues driving the northern spotted owl to extinction."

Spotted owls became the symbol of the timber industry's decline after they were listed as threatened under the Endangered Species Act more than 20 years ago. A 1990 report estimated logging had reduced the owl's favored old-growth habitat by up to 88 percent.

In recent years, however, wildlife biologists concluded that barred owls are a more immediate threat to spotted owls than habitat loss.

Barred owls are native to the East Coast and advanced slowly with settlers. They were reported in Montana by 1909, British Columbia by 1959 and in Washington and Oregon by the early 1970s.

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Biologists believe the Northwest's barred owl now "completely overlaps" the spotted owls' range. The latter are declining at a rate of nearly 3 percent a year, according to the Fish and Wildlife Service.

While spotted owls nest in old growth forests and prefer to eat flying squirrels, barred owls are more flexible. Old growth is their first choice of habitat, but they'll live in younger forests and even city parks. They eat a variety of rodents and small mammals.

In the wild, territorial barred owls harass or even kill spotted owls. A Washington timber company biologist once compared the competition to a "generalist" -- barred owls -- against a "specialist" -- spotted owls.

In deciding to remove barred owls, Fish and Wildlife officials drew upon the work of Lowell Diller, a wildlife biologist with Green Diamond Resource Co. in the redwoods of Northern California.

Working under a federal permit, Diller and other researchers killed 73 barred owls on the private timber company's land from 2009 to 2012. In every case Diller knows of, spotted owls returned to historic nesting areas. In one case, a pair of spotted owls that hadn't been seen for more than two years reappeared 10 days after a pair of barred owls were shot.

Green Diamond owns forestland over about a 100 mile stretch from Eureka north to the Oregon border. Diller has monitored spotted owls in the company's forests for 23 years, and believes very few would be left if barred owls hadn't been removed.

He believes killing barred owls in the four experiment areas is worth a try.

"The alternative," he said, " is to give up on conservation of spotted owls."

The question to be answered, he said, is the long-term feasibility of reducing and controlling barred owls over the spotted owls' full range, from Northern California to British Columbia.

Letting spotted owls go extinct is "not a good alternative when you consider how much resources we've already committed" in recovery efforts, Diller said.

Wildlife officials have intervened with other species, such as removing or killing California sea lions that eat threatened salmon bunched up at Bonneville Dam on the Columbia River. They've killed cormorants and terns that feed on juvenile salmon and steelhead in the Columbia, and Oregon also offers a bounty on northern pike minnows, which eat young salmon.

Barred owl removal will take place in the Cle Elum area of Washington state, in the Coast Range/Veneta and Union/Myrtle areas of Oregon, and the Hoopa/Willow Creek areas of northern California. For comparison, each removal area will be paired with a control section where barred owls are not killed.

The removal plan is a "preferred alternative" that will become final after 30 days. Bown, the biologist in charge, thinks the experiment will work.

"I personally believe we'll see an improvement in our spotted owl population where we remove barred owls," she said. "What we don't know is how we'll keep them out the area -- the feasibility and efficiency and efficacy of the process."